CD8 positive lymphocytes (TCD8+) play an important role in host immunity to viruses and other intracellular parasites. Anti-viral TCD8+ recognize peptides derived from a cytosolic pool of viral proteins. Induction of anti-viral TCD8+ responses is limited by the requirement that the antigen be delivered to the cytosol of antigen presenting cells in vivo. Using infectious vaccines, this is accomplished as part of the infectious cycle of the immunogen. Non- infectious vaccines (inactivated virus, subviral preparations) often fail to induce TCD8+ responses due to their inability to deliver antigens to the cytosol. It should, however, be possible to induce TCD8+ responses to non-infectious antigens if the antigen is modified in such a way as to allow its efficient delivery to the cytosol. To explore this vaccine strategy we studied a model antigen (ovalbumin) that we chemically conjugated to folic acid. By targeting proteins to folic acid receptors, it is believed that this modification facilitates the delivery of proteins to the cytosol. In the past year we studied the presentation of folic acid-conjugated ovalbumin to ovalbumin- specific TCD8+. We failed to obtain evidence that folic acid is able to deliver ovalbumin to the class I antigen processing pathway. In an effort to develop other novel vaccines for eliciting TCD8+ we created a number of recombinant vaccinia viruses that express antigenic peptides in the absence of flanking residues or at the COOH terminus of a sequence that directs the peptides to the endoplasmic reticulum. Preliminary testing of these recombinants in two distinct systems indicates that these recombinants more efficiently elicit TCD8+ responses than traditional recombinants expressing full length gene products.